Refrigerated car



March 28, 1950 H. v. WILLIAMSON 2,502,192

REFRIGERATED cm Filed Sept. 13, 1945 4 Sheets-Slheet 1A March' 28, 1950 H. v1. WILLIAMSON REFRIGERATED CAR 4 Sheets-Sheet 2 Filed Sept. 13, 1945' H. v. WILLIAMSON REFRIGERATED CAR March 28, 1950 4 Sheets-Sheet 3 Filed sept. 1:5, 1945 A TTORNAY March 28,' 1950 H. v. wlLLlAmsoN REFRIGERATED CAR 4 Sheets-Sheet 4 Filed Sept. 13. 1945 Patented Mar. 28, 1950 REFRIGERATED CAR miam; v. Williamson, chicago, nl., assigner to Cardox Corporation, Chicago, Ill., a corpora.-

tion of Illinois Application September 13, 1945, Serial No. .615.946

23 Claims. (Cl. (i2-91.5)

This invention relates to refrigerated railway cars and more particularly to a, method and apparatus which employ Dry Ice as the cooling substance for refrgerating such cars.

Dry Ice has come into recently widespread use in place of water ice to refrigerate the interior of railway cars used for the transportation of perishable products which require refrigeration. Dry Ice has been proposed instead of water ice, because of the increased refrigerating effect obtained from `it compared to that obtained from the same Weight of water ice, and because the lower temperature of the Dry Ice makes it possible to reduce the temperature within the car interior to a level which will reduce the spoilage of the goods. The invention has particular application to the refrigeration of frozen goods during their shipment.

The use of Dry Ice hasy however, involved some disadvantages because if it is exposed directly to the atmosphere within the car interior, it may reduce the temperature of that atmosphere to such a low degree as to harm the food products, and it is also wasteful of the refrigeration obtainable from the Dry Ice. Moreover, the carbon dioxide gas which comes into contact with the food products in many instances will have an injurious effect upon them. Difficulty has also been experienced in obtaining sufficient circulation of the air within a refrigerated space with the result that there has been improper distribution of the refrigeration Within the car interior.

Numerous methods of forced air, or other gases, such as carbon dioxide, circulation have been proposed and tried, some requiring fans operated by motors, movement of the car, or outside wind movement. Other methods wherein liquids, such as brine, are circulated to distribute the refrigeration have been proposed. Some of these methods depended upon natural thermal convection, which has been insufficient to be entirely satisfactory. Other methods have depended upon the motion of the car or pumps for brine circulation.

Since it is highly desirable that the refrigeration of the car-be independent of the motion of the car or outside air, since the car may be standing still, and that no auxiliary power supply or motors be required, the above practices have been generally unsatisfactory. The -problem of control of the circulation of the air or liquids has been not entirely solved.

In accordance with the present invention, Dry Ice is used as the refrigcrating medium to cool the interior of a railway car and as an important feature of the invention the refrigerating effect is 2 distributed substantially uniformly throughout the car space.

As a further feature of the invention, the car interior is cooled throughout its extent without requiring the employment of equipment such as motors or air driven fans.

Another feature of the invention is the provision of means which will automatically regulate the cooling effect within the car space so that the space will be lowered to a safe temperature, but will not be reduced to such a low temperature that the Dry Ice will be Wasted.

A still further feature of the invention involves the provision of a Dry Ice container which may be sealed so that there will be a build-up of carbon dioxide gas pressure within the container so that this gas under pressure may be employed to obtain an improved refrigerating effect.

Another important feature of the invention involves the provision of means for assuring continued refrigeration in the event that some element of the equipment fails to function properly.

Further features of the invention will be apparent from the following description when cons'idered with the accompanying drawings.

In the drawings:

Figure 1 is a plan view of a refrigerated car to which the invention is applied, the roof of the car being removed to show the interior arrangement of the cooling apparatus,

Figure 2 is a side elevation of Figure 1, the near side wall of the car being removed,

Figure 3 is a section on the line 3-3 of Figure 1,

Figure 4 is an enlarged view of the piping system for carrying the sublimed carbon dioxide gas,

Figure 5 is an elevation on an enlarged scale of one of the Dry Ice containers, of the side facing toward the car interior,

Figure 6'is a partial section on the line 6 8 of Figure 5, on an enlarged scale,

Figure '7 is a partial section on the line 1-1 of Figure 6,

Figure 8 is a partial section on the line 8 8 of Figure 5, and

Figure 9 is a section on the line 9-9 of Figure 5 through the upper portion of one of the Dry Ice containers.

It is intended that the refrigerating apparatus of the invention be employed with a railway car having walls I0 which are thermally insulated. This includes the bottom, side and top walls of the refrigerated car. The contents of the car are intended to rest upon a false bottom or floor Il so that an air space is presented immediately below the goods. The iloor II does not extend to the side walls of the car, as appears from Figure 3, to permit the cold air to enter into the air space below the floor. This air space below floor II has the important function of increasing the circulation of air aroi'nd the goods and providing a cool space below the lading which will maintain its bottom surfaces at a low temperature.

At one end of the car space are positioned two Dry Ice containers I2 and I3. As these containers are duplicates of each other and the refrigerating system associated with each container is a. duplicate of the other, only one of these systems will be described. It should be observed, however, that the Dry Ice containers I2 and I3 are side by side across the width of the car in-.

terior at one end thereof. From the container I2 a duct I4 extends in a closed circuit throughout the length of the car and from the container I3 a similar duct I5 extends in a closed circuit also throughout the length of the car. 'I'he ducts I4 and I5 lie close to but nevertheless spaced from the roof` of the car and they are side by side, as appears from Figure 1, so as to occupy each a lateral half of the upper space within the car corresponding to vthe portion of the car width occupied by the container I2 or I3 with which each is associated.

Considering the container I2 and its duct system I4 as representative of both refrigerating systems, the container I2 is enclosed with a reinforcing framework so that the container itself may be made of relatively thin metal and will withstand the pressure imposed by the subliming carbon dioxide. This reinforcing framework includes angle irons I6 along the upright edges of the container and angle irons I1 around the upper and lower edges of the container. Extending between the upper and lower angle irons I1 and lying parallel to the vertical angle irons I6 are reinforcing bars I8. These bars I8 are disposed with their narrow edges toward the container so that they will have an increased pressure sustaining effect. Surrounding the container I2 and lying close to the container within the framework is insulation I9.

For a purpose which will later be explained in detail, it is desired that the subliming carbon dioxide gas build up a pressure within each container. To provide a tight container the invention contemplates the provision of a closure which will tightly seal the opening of the container. It is furthermore important that the means which eiects the seal between the closure and the container be at a thermally isolated point from the interior of the container so that this 1seal will not be cooled to such an extent thatY it will cause condensation of moisture from the air thereon. If the seal were to become so cooled by the Dry Ice within the container that moisture condensed on this seal from the surrounding air, a layer of ice might build up at this seal which would make it diilicult to remove the closure. In accordance with the invention, the seal will remain suiiiciently warm so that no layer oi ice will build up which will resist separation of` the closure from the container. y As is shown in Figure 9, the container I2 is formed at its opening with a riser portion 2|. To the top of the riser portion 2| is clamped an annular gasket 22 and an outer ring 23, by means of bolts 24 which pass through them and screw into Athe wall of the container I2.

The ring 23 has an outer depending skirt which provides an outer cylindrical surface 23 which is intended to be highly polished and smooth.

It will be observed that the ring 23 and the depending skirt thereof providing the polished surface 25 is thermally insulated from the wall of the container I2. The insulation I3, around the riser portion 2I of the container, and the insulation provided by the gasket 22 prevent the direct conduction of heat between the container I2 and the ring 23 except for the slight amount which passes through the retaining bolts 24.

The closure includes a cover plate 26 having a depending flange portion 21 which lies outside of the polished surface 25. At the lower end of the depending flange 21, the closure is ared outwardly to provide a ring-shaped portion 28. An annulus 30 is drawn toward the ring portion 28 by means of clamping bolts 3I, and between the annulus 30 and ring member 28 are sealing gaskets 32 and 33. The gasket 32 should be of a size to bear firmly at its inner face against the polished surface 25 and the gasket 33 is preferably made suiiciently large so that it will be forced to assume a curved position, as shown in Figure 9, when the flange 21 is moved downwardly Ainto place over the polished surface 25.

Attached to the\center portion of thc closed plate 26 by means of a dished member 34 is insulation 35. This dished member 34 lies slightly away from the inner wall of the, riser portion 2| at the opening of container I2, so that if any moisture condenses upon these opposed surfaces, it will not bind the closure and prevent its removal. The seal established by the gaskets 32 ture into the space between the closure and the riser portion 2| of the container I2, and in addition, the gaskets 32 and 33 prevent the escape of carbon dioxide from the interior of the container. In this respect, it will be observed from Figure 9 that the pressure of the carbon dioxide gas tends to force the distorted portion of gasket 33 more firmly against the polished surface 25 so that a tighter seal is effected.

To hold the closure downwardly upon the container I2, there are provided plates 36 which are attached to the cover plate 26, adjacent to its periphery. To cooperate with each of the plates 36 bracket 31 having an overhanging upper edge 38 is attached to the framework at the top side of the container I2. In the arrangement here shown, there are iourof the plates 36 and a corresponding number of the brackets 31. The closure may be turned by means of handles 39, to a position which will bring the plates 36 under the overhanging edge 33 of brackets 31 so that the closure will be held down upon the container. Or, by turning th'e closure so as to position the plates 36 apart from the overhanging edge 38 of brackets 31, the closure may be lifted upwardly away from the opening in the container I2. When the closure is lifted up, the ring 28 and parts attached thereto will pass inside of the overhanging edges-38.

lTo provide a gas escape opening through the closure a conduit 4|! is provided, and its upper end is closed by a valve 4I. Valve 4I is urged against the upper end of the conduit 40 by means o1' a spring 42 so that a pressure of carbon dioxide 'o gas will build up within the container, but this valve 4I will be lifted away from the opening 40 against the action of spring- 42 if an excess pressure occurs. Spring 42 acts between the valve head 4I and the cross member oi a brace 43 attached to cover plate 26. This cross member also and 33 eiIectively prevents the entrance of moisacts as a guide for the upper end of the valve stem. The valve 4| thus serves as a relief valve so that the container will not be damaged by an excessive pressure.

In addition, the valve 4| serves as a manually operable pressure release valve so that the pressure within the container can be reduced to atmospheric conditions so that the closure may be more easily rotated to disengage the locking plates 36 from the brackets 31. To permit the manual operation of valve 4| to release the internal pressure in the container I2, the valve stem is pivoted at 44 to a hand lever 45. Lever 45 is pinned at 46 to an upright on the brace 43 so that lifting of the handle end of lever will lift the valve 4| from its closing position upon the conduit 48. The bottom wall of the container I2 slopes downwardly toward the side wall of the railway car, as is shown in Figure 7. to carryI to this lower side any moisture which might condense in or be carried in the container with the Dry Ice. A self-closing drain valve 41 entering through the bottom Wall of the container I2 at this lower side delivers the water through a conduit 48 to a point below the bottom wall of the railway car.

Below the bottom wall of the container I2 is a closed chamber 56 having a bottom wall 5I. The duct I4 includes portions 52 and 53 thereof (Figures 5 and 7) lying aside of each other and disposed immediately below the chamber 50. The duct portions 52 and 53 together are as wide as the chamber 50 and these portions are separated by a vertical partition 54. The duct portion 52 communicates with the chamber 50 through an opening 55 in the wall 5I at one far side of the chamber 50 and the duct portion 53 communicates with the other far side of chamber 50 through an opening 56 at the other side of the wall 5|. The gas must, therefore, ilow throughout the length of chamber 50 as it enters through opening 55 from duct portion 52 and passes out through opening 56 into duct portion 53.

The duct portions 52 and 53 communicate respectively with vertical duct portions 51 and 58 which lie against the wall of the container I2 which faces toward the interior of the railway car. With this arrangement these upwardly passing portions of the duct transmit heat directly through the wall of the container I2 to the Dry Ice therein. Between these upwardly rising portions 51 and 58 of the duct system and the interior of the railway car is an insulating vertical wall 60 so that the contents of the interior of the car at this end will not be excessively refrigerated The upwardly rising portion 51 of the duct system is connected to a horizontal duct portion 62 and the upwardly rising portion 58 is connected to a horizontal portion 63. These horizontal portions 62 and 63 are connected together at their far ends by a loop 64. If it is desired to increase the heat transmission to the portions 62, 63 and 64 of the duct system, iins may be provided on these portions.

The gas is intended to flow through the duct portion 62 toward the container I2, and downwardly through the vertical portion 51 into the duct portion 52 below the chamber 50. This gas passes upwardly through the opening 55 into chamber 50 and along the bottom wall of the container where it delivers its heat to the Dry Ice in the container. To accentuate the transfer of heat, fins 65 extend downwardly from the bottom wall of the container into the chamber 50 and ilns 66 extend upwardly from this wall into the container I2. If desired. the ns and 66 may be in one piece extending through openings formed in the bottom wall of the container and secured in place so that no leakage of gas from the container I2 into the chamber 56 can take place. It will be noted that the ns 65 extend in the general direction of iiow of gas through the chamber 56 so that but slight impedance to the now of the gas is offered.

The cooled gas passes out of the chamber 50 and into the-duct portion 53 through the opening 56. From the duct portion 53 the gas passes upwardly through the vertical duct portion 58 and into the horizontal duct portion 63 from which it passes around the loop portion 64 and into the return duct portion 62. Thus, the gas ilows in a closed circuit through the duct system and its portions within the car space absorb heat from the surrounding air, this heat being given up to the Dry Ice through the duct portions adjacent to container I2.

To stimulate circulation of the gas in the duct system in the direction discussed, the duct system includes an aspirator section. This aspirator section may be located at any desired place along the duct system, but as here shown, it is located in the horizontal duct portion 63. The aspirator section is formed by reducing the crosssectional area of the duct 63 at 61 (Figure 1) to form a venturi.

As an important feature of the invention, the Venturi portion of the duct 63 is formed by reducing the width only of this duct. The restricted portion 61 is, therefore, of substantially the same height as the height of the remaining portions of the duct system, but the sides of the duct 63 yare brought together to the restricted portion 61 so that the venturi formed. This makes it possible to have ducts 62 and 63 of oblong shape in cross-section so that they can be disposed ilatwlse toward the roof of the car and thus take up a minimum headroom. It has been found that a Venturi section can be formed in a duct of this shape by maintaining the height of the duct and merely reducing its width.

A pipe 68 is positioned to direct gas under pressure directly into the restricted portion 61 so that an aspirator effect is accomplished. Pipe 68 is supplied with gas under pressure by connection to a pipe 69 which enters the container I2. Within the pipe 69 is a valve 10 which remains closed until the pressure within the chamber I2 has built up to a value which will satisfactorily operate the aspirator at 61. This valve may be set to open, for example, at approximately five pounds per square inch pressure and to close at approximately four andv one-half pounds per square inch pressure. For best results. it is desirable that the valve 10 be of the tvre which opens rapidly when the desired maximum pressure is reached, and closes rapidly when the pressure has dropped to the set minimum. It will be appreciated that the relief valve 4| should open only at a pressure somewhat in excess of the pressure at which valve 10 is intended to open.

Communicating with the pipe 69 is a branch pipe 1".. flow through which is controlled by a. valve 13. and which enters the duct system at arpr point. as for example. directlv into the duct portion 62. Valve-13 is controlled by a thermostaf, 14 which should preferably be located close to the top of the car space to be refrigerated and at a point substantially midwav of is length.

It is intended that the thermostat 14 serve to cause the valve 13 to be closed when the temawait-2 perature within the space to be refrigerated is too high. This will cause all of the gas passing through the pipe 69 and valve 10 to enter the pipe 68 and be directed into the Venturi portion at 61 to cause an aspirator action. This aspirator action will cause a stimulated flow of the gas within the duct system so that the heat absorbed by the gas in this duct will be more rapidly carried to the Dry Ice in the container l2 through the action of the iins 65 and 66.

When the temperature of the space has been cooled to the desired low temperature, the

-thermostat 14 will function to open the valve 13 so that the gas passing through the pipe 69 and the valve 10 will be delivered through the branch pipe 12 directly into the duct system and will not ow in any effective amounts to the pipe 68 which is directed into the Venturi portion of the duct. As the gas which by-passes the aspirator pipe 68 and ows through the branch pipe 12 directly into the duct 62 has no aspirator action, it will not serve to induce a iow of the gas through lthe duct system. As a consequence of reduced flow of gas through the duct system, there will not be as rapid a transfer oi' heat to the Dry Ice`;and consequently the refrigerating effect will be decreased until the temperaure rises to that which causes the thermostat 14 to close the valve 13.

The carbon dioxide gas entering the duct system through the branch pipe 12 will, however, serve to maintain the gas within the duct at a low temperature so that the cooling effect oi this sublimed gas will not be lost and the maximum refrigerating effect will thereby be obtained from the Dry Ice. As the carbon dioxide gas from the Dry Ice is constantly being delivered to the interior of the duct system, it maintains the duct sysem full of this gas. As gas is being constantly delivered to the duct system, the duct must be vented and this is accomplished by a pipe 15 which enters the duct system at 18 and has an escape opening at 11 at the opposite end of the car. The pipe 16 preferably enters the duct portion 62 just before its connection to the down portion 51 as this removes the warmest gas from the system. By having pipe 15 long, as shown. it serves to minimize entry of atmospheric moisture into the duct system.

Although it is preferred that the branch pipe 12 deliver the carbon dioxide gas into the duct system as this conserves the cooling effect to be obtained, lthis pipe may vent to any point apart from the duct as this will reduce the flow through pine 68 to the aspirator. Or, the ow of carbon dioxide gas through pipe 68 may be varied by a temperature responsive valve in pipe 68 or 69, but it is preferred to by-pass the gas into the duct in the manner explained.

Beneath the horizontal duct portions 62 and 63 and extending throughout the length of these portions is a tray 18 which is intended to receive the moisture which may condense on and drop off of the duct portions 62 and 63. This tray 18 is inclined downwardly and away from the long side wall of the car. and at its edge toward the center of the car space it is formed with a gutter 19. The water which collects in the gutter 19 is delivered therealong to the ends of the tray 18 from which points it may be carried through downwardly extending pipes 80 to and out through the bottom wall of the railway car.

To permit access to the closure for the container I2, an opening is formed in the roof of the railway car and this opening is closed by a cover 82. It is preferable that this cover l2 be not too well insulated as the parts constituting the seal between the container l2 and its closure will not become so cooled that moisture will freeze out on them and resist removal of the closure. It will be understood that the closure for the container I3 is available through an opening in the roof of the car directly thereabove and which is closed by a cover similar to the cover 82.

The provision of the two complete refrigerating systems with separate Dry Ice containers and their independent duct systems, each with its own temperature control. is desirable to provide the optimum operating safety. In the event of failure of the one system the other will operate effectively.

If the refrigerated car is to contain frozen foods, it is intended that the temperature controlled valve 13 be of a type which, if it fails at all, will fail in the closed position so that all of the sublimed gas of that particular system will be delivered to the aspirator pipe 68 so that ow of gas through the duct system will be induced. In this way, this system will continue to i'unction and the other system will probably not function at all, so that its Dry Ice will be saved until the complete exhaustion of the dry ice within the system which has had a valve failure. Thereafter, the other system in which the Dry Ice has not been used up will take over normal operation. This arrangement may possibly cause the car to become slightly undercooled, but this is preferable to letting the space become too warm in the case of frozen foods.

If the refrigerated car is to contain non-frozen fresh foods which would be damaged by freezing, it is advisable that the valve 13 be of a type which if it fails will do so in the open position. The sublimed gas can then flow directly into the duct through the branch pipe 12 and the effectiveness of the aspirator action will be minimized so that the fresh foods which may be harmed by freezing will not be undercooled.

What is claimed is:

l. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a duct looped within the interior of the car and extending in a closed circuit into thermal contact with the wall of the container, said duct having a restricted portion to constitute a Venturi section, and a conduit for delivering carbon dioxide gas under pressure from within said container to the Venturi section of the duct to stimulate circulation through the duct.

2. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed Within the car interior, a duct looped within the interior of the car and extending in a closed circuit into thermal contact with the wall of the container, said duct and said container having a wall in common, ns projecting from said common wall into said container and also into the duct, said duct having a restricted portion to constitute a Venturi section, and a conduit for delivering carbon dioxide gas under pressure from within said container to the Venturi section of the duct to stimulate circulation through the duct.

3. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a duct looped within the interior of the car and extending in a closed circuit into thermal contact with the wall of the container, said duct being pressure from within said container to the Venl turi section of the duct to stimulate circulation through the duct.

4. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car-interior, a duct extending in a closed circuit from a point in thermal contact with the bottom wall of the container t the interior of the car, the supply and return sections of the duct having horizontal portions positioned aside of each other close to the ceiling of the car interior and having vertical portions positioned aside of each other along a side wall of the container, said duct having a restricted portion to constitute ka Venturi section, and a conduit for delivering carbon dioxide gas under pressure from within said container to the Venturi section of the duct to stimulate circulation through the duct.

5. Apparatus for refrigerating Athe interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a duct extending in a closed circuit from a point in thermal contact with the bottom wall of the container to the interior of the car, the supply and return sections of the duct having horizontal portions positioned aside of each other close to the ceiling of the car interior and having vertical portions positioned aside of each other along a side wall of the container, said duct being oblong in cross section andlying atwise toward the ceiling and side wall of the container, said duct having a restricted portion to constitute a Venturi section, and a conduit for delivering carbon dioxide ga's under pressure from within said container to the Venturi section of the duct to stimulate circulation through the duct.

6. Apparatus for refrigerating the interior ot a railway car, which comprises a container for Dry Ice disposed,within the car interior, a chamber having its upper wall common with the bottom of the container to provide indirect heat exchange therebetween, and a duct looped within the interior of the' car and having its supply and return sections arranged side-by-side and extending beneath said chamber, said chamber communicating with the supply and return sections respectively at opposite sides of the chamber whereby gas iiow may occur throughout the length of the chamber.

7. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a chamber having its upper-wal1 common with the bottom of the container to provide indirect heat exchange therebetween, a d-uct looped within the interior of the car and having its supply and return sections arranged side-by-side and extending beneath said chamber, said chamber having bottom openings at opposite sides thereof to aord communication with the supply and return sections respectively whereby gas flow may occur throughout the length of the chamber, and fins projecting into said chamber from the bottom wall of the container and extending in the direction of flow of gas through the chamber.

8. Apparatus for refrigerating the interior of a railway car, which comprises a container duct extending in a closed circuit from a point in thermal contact with the container to the interior of the car, the portion of the duct within the car interior being oblong in cross-section and lying ilatwise toward and close to the car ceiling, said duct being narrowed in width to form a restricted portion constituting a Venturi section, and a conduit for delivering carbon di: oxide gas Iunder pressure from within said container to the Venturi section to stimulate circulation through the duct.

9. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a duct extending in a closed circuit from a point in thermal contact with the container to the interior of the car, the portion of the duct within the car interior being oblong in cross-section and lying ilatwise toward and close to the car ceiling, said duct being narrowed in width to i'orm a restricted portion substantially square in cross-section constituting a Venturi section, and a conduit for delivering carbon dioxide gas under pressure from within said container to the Venturi section to stimulate circulation through the duct.

10. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a duct extending in a closed circuit from a point in thermaly contact with the container to the interior of the car, the portion vof the duct within the car interior leading away from the container being restricted in cross-section to constitute a Venturi section, a conduit for delivering carbon dioxide gas under pressure from within said container to the Venturi section to stimulate circulation through said duct, said duct having an escape opening in the return portion adjacent to the container.

11. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a duct looped within the interior of the car and extending in a closed circuit into thermal contact with the wall of the container, said duct having a restricted portion to constitute a Venturi section, means for sealing the container to obtain a pressure of sublimed carbon dioxide therein, and a conduit for delivering carbon dioxide from within said container to the Venturi section to stimulate circulation through the duct by an aspirator action, said conduit having a valve therein openable by the carbon dioxide pressure only after it has reached a predetermined minimum.

12. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a duct looped within the interior of the car and extending in a closed circuit into thermal contact with the wall of the container, said duct having a restricted portion to constitute a Venturi section, means for sealing the container to obtain a pressure of sublimed carbon dioxide therein, a conduit for delivering carbon dioxide from within said container to the Venturi section to stimulate circulation through the duct by an aspirator action, said conduit having a valve therein openable by the carbon dioxide pressure only after it has reached a predetermined minimum, and a valve in said conduit on the low pressure side of the first mentioned valve tovent the conduit when the car interior is too cold to thereby re- Ior Dry Ice disposed within the car interior, a duce the aspirator action.

13. Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a duct looped within the interior of the car and extending in a closed circuit into thermal contact with the wall oi the container, said duct having a restricted portion to constitute a Venturi section, means for sealing the container to obtain a pressure of sublimed carbon dioxide therein, a conduit for delivering carbon dioxide from within said container to the Venturi section to stimulate circulation through the duct by an aspirator action, and means for varying the ilow through the duct to control the refrigerating action.

14, Apparatus for refrigerating the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior. a duct looped within the interior of the car and extending in a closed circuit into thermal contact with the wall of the container, said duct having a restricted portion to constitute a Venturi section, means for sealing the container to obtain a pressure of sublimed carbon dioxide therein, a conduit for delivering carbon dioxide from within said container to the Venturi sectionto stimulate circulation through the duct by an aspirator action, and means for varying the iiow of carbon dioxide delivered into the Venturi section from said conduit to thereby regulate the ow through the duct and control the refrigerating action.

15. Apparatus for refrigeratlng the interior of a railway car, which comprises a container for Dry Ice disposed within the car interior, a duct looped within the interior of the car and extending in a closed circuit into thermal contact with the wall of the container, said duct having a restricted portion to constitute a Venturi section, means for sealing the container to obtain apressure of sublimed carbon dioxide therein, and a conduit for delivering carbon dioxide from within said container to the Venturi section to stimulate circulation through the duct by an aspirator action, said conduit having a valve controlled branch pipe to vent the conduit when the car interior is too cold and to thereby reduce the aspirator action. i.

16. The method of refrigerating the interior of a railway car which comprises circulating a gas through a closed circuit now path in heat exchange relation with the cargo space of a railway car, cooling the gas at one point in its flow path by thermal Contact with Dry Ice contained in a coni-ined space, stimulating ow of gas through said ow path by delivering sublimed carbon dioxide from said conned space to said flow path at a relatively high velocity, and varying the ilow in said ow path to thereby control the refrigerating action.

17. The method of refrigeratirig the interior of a railway car which comprises circulating a gas through a closed circuit flow path in heat exchange relation with the cargo space of a railway car, cooling the gas/at one point in its flow path by thermal contact with dry icecontained in a confined space, stimulating ow oi.' gas through said iiow path by delivering sublimed carbon dioxide from said conilned space to said flow path at a relatively high velocity, and varying the ow delivering of carbon dioxide from said conned space to thereby vary the flow through the flow path and control the refrigerating action.

18. The method of refrigerating the interior of a railway car which comprises circulating a gas through a closed circuit now path in heat exlow velocity to reduce the refrigerating action when the car interior becomes too cool.

19. The method of refrigerating the interior of a railway car which comprises confining solid carbon dioxide under a desired gas pressure in an end space of the car that is insulated from the portion of the interior of the car which is to be refrigerated; circulating carbon dioxide gas through a plurality of closed circuit iiow paths which include shallow portions that substantially ll a horizontal section of the said interior of the car adjacent its ceiling, portions that substantially ll a vertical section of the said insulated end space with the section being located between the cbniined solid carbon dioxide and the refrigerated interior of the car, and additional portions that substantially fill a horizontal section of the said insulated end space with the section being located beneath the confined solid carbon dioxide; absorbing heat from the interior of the car by means of the carbon dioxide gas passing through the portions of said iiow paths located adjacent the car ceiling; and removing the absorbed heat from the carbon dioxide gas while it passes through the portions of the iiow paths located in the insulated end space of the car.

20. The method of refrigerating the interior of a railway car which comprises confining solid carbon dioxide under a desired gas pressure in an end space of the car that is insulated from the portion of the interior of the car which is to be refrigerated; circulating carbon dioxide gas through a plurality of closed circuit flow paths which include shallow portions that substantially iill a horizontal section of the said interior of the car adjacent its ceiling, portions that substantially ll a verticai section of the said insulated end space with thesection being located between the conned solid carbon dioxide and the refrigerated interior of the car, and additional portions that substantially iill a horizontal section of the said insulated end space with the section being located beneath the confined solid carbon dioxide; absorbing heat from the interior of the car by means of the carbon dioxide gas passing through the portions of said ow paths located adjacent the car ceiling; removing the absorbed heat from the carbon dioxide gas while it passes through the portions oi the iiow paths located in the insulated end space of the car, and delivering carbon dioxide gas resulting from sublimation of the conned solid carbon dioxide to each of said iiow paths to stimulate movement of the carbon dioxide gas in said paths.

21. The method of refrigerating the interior of a railway car which comprises coniining solid carbon dioxide under a desired gas pressure in an end space of the car that is insulated `from the.

refrigerated interior of the car, and additional portions that substantially ll a horizontal section of the said insulated end space with the section being located beneath the confined solid carbon dioxide; absorbing heat from the interior of the car by means of the carbon dioxide gas passing through the portions of said flow paths located adjacent the car ceiling; removing the absorbed heat from the carbon dioxide gas while it passes through the portions of the iiow paths located in the insulated end space of the car, and accelerating the transfer of heat from the carbon dioxide gas to the confined solid carbon dioxide while the gas is passing through the portions of the iiow paths that are located beneath the coniined solid carbon dioxide.

22. The method of reirigerating the interior of a railway car which comprises coniining solid carbon dioxide under a desired gas pressure in an end space of the car that is insulated from the portion of the interior of the car which is to be refrigerated; circulating carbon dioxide gas through a. plurality of closed circuit flow paths which include shallow portions that substantially fill a horizontal section of the said interior of the' car adjacent its ceiling, portions that substantially ll a vertical section of the said insulated end space with the section being located between the confined solid carbon dioxide and the refrigerated interior of the car, and additional portions that substantially iill a horizontal section of the said insulated end space with the section being located beneath the conned solid carbon dioxide; absorbing heat from the interior of the car by means of the carbon dioxide gas passing through the portions ofv said iiow paths l located adjacent the car ceiling,- removing the absorbed heat from the carbon dioxide gas while it passes through the portions of the flow paths located in the insulated end space of the car and with the transfer of heat from the carbon dioxide gas to theconiined solid carbon dioxide being accelerated while the gas is passing through the portions of the flow paths that are located beneath the confined solid carbon dioxide, and delivering carbon dioxide gas resulting from sublimation of the confined solid carbon dioxide to each of said flow paths to stimulate movement of the carbon dioxide gas in said paths.

23. The method of refrigerating the interior of a railway car which comprises confining solid carbon dioxide under a desired gas pressure in an end space of the car that is insulated from the portion of the interior of the car which is to be refrigerated; circulating `carbon dioxide gas through a plurality of closed circuit flow paths which include shallow portions that substantially iill a horizontal section of the said interior of the car adjacent its ceiling, portions that substantially iill a vertical section of the said insulated end space with the section bein-g located between the coni-ined solid carbon dioxide and the refrigerated interior of the car, and additional portions that substantially iill a horizontal section of the said insulated end space with the section being located beneath the coniinedsolid carbon dioxide; absorbing heat from the interior of the car by means of the carbon dioxide gas passing through the portions of said iiow paths located adjacent the car ceiling; removing the absorbed heat from the carbon dioxide gas while it passes through the portions of the flow paths located in the insulated end space of vthe car and beneath the confined solid carbon dioxide, and delivering carbon dioxide gas resulting from sublimation of the confined solid carbon dioxide to one of the shallow horizontal portions of each of said flow paths to stimulate movement of the carbon dioxide gas in said paths.

HILDING V. WILLIAMSON.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,925,537 Killeffer Sept. 5, 1933 1,926,700 Owens Sept. 12, 1933 1,933,135 Barthelmes Oct. 31, 1933 2,012,892 Rice Aug. 27, 1935 2,061,116 Thornton Nov. 17, 1936 2,067,324 Jones et al Jan. 12, 1937 2,071,798 Lewis Feb. 23, 1937 2,263,653 Smith Nov. 25, 1941 y FOREIGN PATENTS Number Country Date 394,253 Great Britain June 22, 1933 

